1. Field of the Invention
The present invention relates to a fan fastening structure for a computer housing. In particular, this invention relates to a fan fastening structure that can rapidly and efficiently exhaust heat in a computer housing to the outside of the computer housing.
2. Description of the Related Art
Inside a computer housing there are a number of circuit boards and electronic components. When the computer is running, heat is generated from the electronic components in the computer housing, such as the chips, the ICs etc, and the temperature rises. If the temperature in the computer housing exceeds the operational specifications of the electronic components, the electronic components will fail and the computer will shut down. Therefore, a cooling fan is usually installed in the computer housing to exhaust the heat generated from the electronic components to the outside of the computer housing.
Reference is made to FIG. 1, which shows a fan fastening structure of the prior art. The fan fastening structure includes a computer housing 10a, a power supply 20a, and a plurality of small cooling fans 30a. There is a backboard 11a on the rear side of the computer housing 10a. The power supply 20a is located on the inner side of the backboard 11a and is adjacent to the top of the backboard 11a. The cooling fans 30a are screwed on the inner side of the backboard 11a by screws 40a, and are located below the power supply 20a. Heat generated in the computer housing 10a is exhausted to the outside of the computer housing 10 via the cooling fans 30a. 
However, because the space of the backboard 11a of the computer housing 10a is limited, the plurality of small cooling fans 30a is merely installed on the available space of the backboard 11a. Because the exhausting capacity of the cooling fan 30a is small, the cooling fans must be operated at high speed to exhaust the heat. Therefore, it is noisy, and the cost of the plurality of small cooling fans 30a is high.